The present invention relates to an ink jet cartridge containing liquid ink, a manufacturing method thereof, an ink jet head and printer using the cartridge, and is usable with a copying machine, a facsimile machine or another recording apparatus, communication apparatus, office equipment, combined machine or printer.
Heretofore, an ink cartridge for an ink jet recording apparatus may have been integrally formed with an ink jet head, and when the ink in the cartridge is used up, the unified head and container are disposed of. The quantity of the ink remaining in the cartridge is decided by the ink retaining capacity of a sponge (vacuum producing material) occupying the entirety of the space in the cartridge, and it is relatively large. Japanese Laid-Open Patent Application No. 87242/1988 discloses such an ink container. The ink container contains a foamed material, and it is integral with an ink jet recording head having a plurality of ink ejection orifices. In such an ink container, in order to accommodate the ink in the porous material such as foamed polyurethane material, the production of the vacuum and the ink retention (prevention of ink leakage from the ink container) are accomplished by the capillary force of the foamed material. However, the foamed material is required to be filled in the entirety of the ink container, and therefore, the quantity of ink therein is limited, and the quantity of non-usable ink is relatively large. This means that the ink use efficiency is low. It is difficult to detect the remaining amount of the ink therein. In addition, during the ink consumption period, the negative pressure gradually changes, and therefore, it is difficult to maintain a substantially constant vacuum.
Japanese Laid-Open Patent Application No. 522/1990 discloses that the ink cartridge contains substantially only the ink. More particularly, it discloses an integral ink jet recording head and ink container, comprising a primary ink container for containing a large amount of the ink at an upper position, and a small porous material between the ink jet recording head therebelow. It is stated that ink use efficiency is improved because only the ink is disposed in the ink passage without the porous material contained in the ink container. In addition, a secondary ink container capable of containing the ink is provided at a side of the porous material, which is effective to receive ink that flows from the primary ink container due to expansion of the air in the primary ink container upon a temperature rise (pressure decrease), so as to maintain a substantially constant negative pressure of the recording head during the recording operation.
In this structure, when the recording operation is not carried out, the porous material is filled with a very large amount of the ink from the primary ink container containing a large amount of the ink above the porous material, and therefore, the porous material itself can hardly produce the negative pressure. For this reason, the ink leaks out of the orifice of the ink jet recording head through only small impacts, and therefore, the structure is not practical. If this container is used as a exchangeable ink cartridge to be mounted to an ink jet recording head, the ink can leak out of the porous material, and therefore, it is still not practical.
In an ink cartridge, the ink may be sealingly contained in a bladder, and the negative pressure of the bladder can be maintained constant using a spring structure, but this is expensive, and it is difficult to mass-produce with the correct performance of the spring structure. In the field of the ink jet printing (non-contact type printing) an inexpensive ink cartridge having proper performance has not been accomplished, and has long been desired.
The inventors have investigated from the standpoint of properly supplying the ink corresponding to the ejection of the ink from the recording head during the printing operation and also from the standpoint of preventing ink leakage through the ejection outlet when the printing operation is not carried out. As a result, it has been found that the fundamental structure comprises a chamber for containing substantially only the ink to be supplied to a second chamber containing a vacuum producing material and having an air vent, the first chamber being substantially hermetically closed with the exception of communicating with the first container.
Japanese Laid-Open Patent Application No. 16385/1982 discloses a recording pen having a recording tip which is contacted to a recording material during the recording operation. The recording tip has an ink absorbing and retaining nature, and the ink is supplied thereto. Therefore, the recording tip is exposed to ambience, as contrasted to the ink jet recording apparatus. This Japanese laid-open patent application is directed only to the overflow of the ink through the recording tip.
It comprises as essential elements a first liquid absorbing material, and a second absorbing material which absorbs less ink than the first absorbing material (although absorbing a small amount of the ink), the second absorbing material being disposed above the first absorbing material at a position closer to an air vent, a central chamber from which the recording tip is projected downwardly, and hermetically closed in accommodating chamber to supply the ink to opposite sides of the chamber. With this structure, when the air in the closed ink container expands due to the ambient temperature rise with the result of the ink in the ink container being forced into the first absorbing material, the ink incapable of being retained by the first absorbing material is absorbed by the second absorbing material, so that overflowing droplets of ink from the writing tip can be prevented. It also discloses provision of a constant width groove which is effective, when one of the two closed ink containers contains only air, to permit the expanded air to escape through the air vent. The groove is extended from the bottom end to the top end on a side surface which is different from a partition wall between the central chamber and the closed ink container. When this structure is used for an ink jet recording head, ink leakage through the air vent has been confirmed, as expected because of the fundamental difference between contact recording and non-contact recording. This problem is not recognized in the field of recording pens. In addition, the constant width groove serves to promote the discharge of ink together with air, therefore promotes ink leakage.
Additionally, the ink consumptions of the two ink containers are not the same. If one of the containers becomes empty first, the ink jet recording operation is no longer possible despite the fact that a large amount of ink is remaining in the other ink container. This is because a large amount of air is introduced into the first-absorbing material with the result of incapacitating the ink supply. This is against the aim of the present invention.
Accordingly, it is a principal object of the present invention to provide an improvement to the fundamental structure having a first chamber containing ink and a second chamber containing the vacuum producing material and provided with the air vent for communication with the ambience, the first chamber being substantially hermetically closed with the exception of the communication with the second chamber. The improvement is intended for effective use for ink jet recording or printing.
It is another object of the present invention to provide an exchangeable ink cartridge, an ink jet head and a printer using the same capable of effecting high speed recording, while the vacuum can be maintained substantially constant in a large part of the period from the start of the use to the end thereof of the ink cartridge.
It is another object of the present invention to provide an exchangeable ink cartridge in which the vacuum is produced in the ink cartridge when the recording operation is not effected, thus preventing ink leakage through an opening upon small impact.
It is a further object of the present invention to provide an ink cartridge in which the remaining non-usable ink is minimized.
It is a yet further object of the present invention to provide an exchangeable ink cartridge which is less expensive and from which the ink does not leak out during transportation of itself.
According to an aspect of the present invention, a region of the vacuum producing material that adjacent to air introduction passage does not contain the ink. By doing so, the leakage of the ink through the air vent from the ink cartridge can be prevented against the ambient condition change. Particularly when a sealing member is used to seal the air vent, this aspect of the invention is effective to prevent removal of the sealing member. During the use of the ink cartridge, this region is effective to ensure that the proper amount of the air is introduced into the ink cartridge, thus suppressing variation of the vacuum in the ink jet cartridge. The region adjacent the air introduction passage is completely free from being wetted by the ink, the ink seeping speed is reduced, and therefore, it is desirable. However, it is a possible alternative that the region is once wetted by the ink, and the ink is thereafter removed.
According to another aspect of the invention based on the above-described fundamental structure, the vacuum or negative pressure producing material is compressed or capable of being compressed in the region adjacent an ink supply opening or an ink supply pipe which is provided at a side opposite from the partition wall having a fine communication part or opening between the first chamber and the second chamber. By doing so, a stabilized ink path can be assured in the vacuum producing material from the first chamber. For the purpose of the further stabilization, the ink supply opening is disposed above the small communication part relative to the bottom surface of the ink cartridge. Here, the supply pipe includes an insertion pipe peculiar to the ink jet recording or printing apparatus, and a valve structure or connecting member mounted on the cartridge compressing the vacuum producing member. By doing so, the ink movement direction can be substantially stabilized, so that all of the ink in the first chamber can be used up. After it is used up, the air moves from the partition wall toward the ink supply opening, thus permitting consumption of the ink in the vacuum producing material, and therefore, the amount of the non-usable remaining ink can be minimized.
According to a further aspect of the present invention, a region of the vacuum producing material not compressed by the supply pipe, and the region compressed by the supply pipe are formed in the order named from the partition wall forming the fine communication part to the opposite wall, by which one way ink supply path is formed in the non-compressed region, and in addition, the remaining non-usable ink amount can be further reduced by the ink retaining capacity in the compressed region.
The present invention includes a structure containing one or more of the above-described aspects.
The ink jet cartridge of this invention is usually handled by an operator, and therefore, it is possible that strong force is applied thereto with the result of deformation of the ink container wall. In view of this, it is preferable that an additional partition wall providing a larger clearance than the fine communication part in the ink chamber for containing substantially only the ink. When the cartridge is made of resin material, it is preferable that the thickness of the wall containing substantially only the ink is 0.8 mm (Ti, G in FIG. 29) or more and that the wall thickness of the container containing the vacuum producing material such as a sponge is 1.3 mm (Ts, J in FIG. 20) from the standpoint of the prevention of the deformation. In the ink jet printer of this invention, the ink is discharged by sucking the ink by the sucking means and by ejecting the ink by ejecting means automatically or manually upon mounting of the cartridge on the ink jet printer. This is preferable because the state of the ink in the vacuum generating material can be adjusted before the start of the printing operation, and therefore, the printing function can be performed without influence by the ink cartridge storage conditions.
In the manufacturing method of this ink cartridge according to this invention, the fine communication part can be provided between a partition wall and a covering member by fixing the covering member accommodating the vacuum producing material in a container, to the main body of the ink cartridge. Thus, the vacuum producing material can be stabilized adjacent the fine communication part, and therefore, the mass-production is easy.
The height of the fine communication part provided by the partition wall is larger than an average pore size of the vacuum producing material (preferably the average pore size in the region adjacent the fine communication part) (practically not less than 0.1 mm), and it is preferably not less than 5 mm. If it is less than 3 mm, the further stabilization can be expected. The volume ratio of the vacuum producing material second chamber and the ink containing first chamber is not less than 1:1 and not more than 1:3, practically.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.